import java.util.Scanner;
public class ScoreLevel{
   public static void main(String[] args){
       Scanner scanner = new Scanner(System.in);
	   System.out.print("please enter the score:");
	   int score = scanner.nextInt();
	   if(score>=90)
	      System.out.println("A");
	   else if(score>=80&&score<90)
	      System.out.println("B");
	   else if(score>=70&&score<80)
	      System.out.println("C");
	   else if(score>=60&&score<80)
	      System.out.println("D");
	   else
	      System.out.println("not passed the test.");
   }
}